Blackboard compass



.J. COLLINS, SR 2,563,309

BLACKBOARD COMPASS Aug. 7, 1951 Filed Sept. 20, 1948 I N VEN TOR ATTC! RN EYS Patented Aug. 7, 1951 UNITED STATES PATENT OFFICE BLACKBOARD COMPASS Jesse Collins, Six, Houston, T,ex.

Application September 20, 1948, Serial No. 50,077

1 Claim. 1

This invention relates to drawing instruments such as used by artists, draftsmen, and the like particularly for drawing or sketching on blackboards and the like, and in particular the invention relates to a compass having a point at the end of one arm with a resiliently lined chalk holding socket in the end of the other arm.

The purpose of this invention is to provide a compass for blackboard use in which a socket is provided in the end of one arm that is provided with means for holding chalk without breaking the same.

Compasses have been provided for holding points, pens. pencils and the like, and whereas pencils have been held in tubular sockets by friction it is difficult, if not impossible to hold chalk and crayons in sockets of this type without breaking the same. With this thought in mind this invention contemplates a compass having an elongated tubular socket with a resilient lining and in which the socket is split and the parts held in clamping relation with a piece of chalk by adjusting and thumb screws in a surrounding band.

The object of this invention is, therefore, to provide means for constructing a comparatively small, inexpensive compass for drawing on blackboards wherein a socket is provided for holding chalk and the like.

Another object of the invention is to provide a chalk holding socket on a compass in which the chalk is gripped at a point adjacent the outer end thereof.

Another object of the invention is to provide an outer end of a compass arm that is adapted to frictionally grip chalk which may be used in compasses now in use.

A further object of the invention is to provide a compass with a chalk holding socket for drawing on blackboards and the like which is of a simple and economical construction.

With these and other objects and advantages in view the invention consists of the new and useful combination, construction, and arrangement of parts as hereinafter more fully described, set forth in the claim appended hereto, and disclosed in the accompanying drawings forming part hereof, wherein:

Figure 1 is a view showing a side elevation of the compass.

Figure 2 is a vertical section through the chalk holding arm of the compass with parts shown in elevation.

Figure 3 is a vertical section through the lower end of the point holding arm of the compass.

Figure 4 is a detail showing a vertical section through the chalk holding socket of the compass on an enlarged scale.

Figure 5 is a cross section through the chalk holding socket taken on line 5-5 of Figure 4.

Figure 6 is a similar section through the point holding arm taken on line 66 of Figure 3.

Referring now to the drawings wherein like reference characters denote corresponding parts the blackboard drawing compass of the invention includes arms l0 and H with outer ends l2 and I3, and with the arms adjustably held by a thumb screw Ill in a U-shaped clamp I5 having a handle it extending upwardly therefrom.

The outer ends l2 and [3 of the arms are provided with tongues I! and 18, respectively, that are held in slots l9 and 20, in the ends of the arms 10 and H, by thumb screws 2| and 22, respectively. The tip of the end I3 is provided with a socket 23 in which a point 24 is adjustably held by a thumb screw 25, as shown in Figure 6.

The chalk holding socket 26 is formed in the end 12 with a split tube 21 having slots 28 and 29 in the sides secured on a shank 30 of the end l2, as shown in Figure 4, and the inner surface of the tube is lined with a sleeve 3| of rubber or the like. The chalk is clamped in the socket by the combination of the adjusting screws 32 and 33 with the thumb screw 34 in a band 35, as shown in Figure 5, and the inner end of the screw 34 is mounted in an opening 36 in the tube 21. With the band 35 spaced from the outer end of the socket the outer end may be drawn slightly together whereby the outer end only, of the chalk will be frictionally held, which will prevent breaking thereof. It will be understood that although the point 24 is illustrated as a conventional steel point, a point of any suitable type may be used in the end 13.

With the parts arranged in this manner a piece of chalk 31 may be clamped in the socket 26 and with the compass held with one hand and the socket guided by a handle 38 thereon a circle may be described on a blackboard or the like.

It will be understood that modifications may be made in the design and arrangement of the parts without departing from the spirit of the invention.

What is claimed is:

In a chalk compass, the combination which comprises a pair of pivotally connected arms with short ends pivotally mounted in the ends of the arms, a point secured by a set screw in a socket in the outer end of one of said short arms, a split chalk holding sleeve extended from and carried by the other of said short ends of the arms, a band positioned around the said split sleeve and spaced from the lower end thereof, a thumb screw threaded in said band and having an end positioned in an opening in the said split sleeve for retaining the said band in position on the sleeve, and spaced adjusting screws threaded in said band and positioned to engage the outer surface of a section of the split sleeve opposite to the Section of the sleeve having the opening therein into which the end of the thumb screw extends whereby gripping action of the split sleeve in relation to chalk positioned in the said sleeve is distributed over a plurality of points around the sleeve and chalk.

JESSE COLLINS, 8:.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 437,250 Schollhorn Sept. 30, 1890 459,519 Collins Sept. 15, 1891 595,607 Coykendall Dec. 14, 1897 702,732 Johnson June 17, 1902 1,216,070 Carlson Feb. 13, 1917 2,074,102 Christy Mar. 16, 1937 FOREIGN PATENTS Number Country Date 5,009 Great Britain 1897 

